Charge fluctuations at the Si–SiO2 interface and its effect on surface recombination in solar cells

Abstract

The Si-SiO2 interface has and will continue to play a major role in the development of silicon photovoltaic devices. This work presents a detailed examination of how charge at or near this interface influences device performance. New understanding is identified on the effect of charge-induced potential fluctuations at the silicon surface. Such fluctuations have been considered in Si-SiO2 recombination models previously, where a universal value of electrical potential deviation was used to represent the effect. However, the approach disregards that the variation occurs in the charge concentration rather than the potential. We modify the models to accurately reflect fluctuations in external charge, allowing a precise representation of surface recombination velocity, with self-consistent !" , # , and $ parameters. Correctly accounting for these parameters can provide insights into the passivation mechanisms which can aid the development of future devices. Using the corrected model, we find that the effect of charge fluctuation at the Si-SiO2 interface is significant for the depletion regime to the weak inversion regime. This indicates that surface passivation dielectrics must operate with charge concentrations in excess of 2x10 12 q/cm 2 to avoid these effects. TCAD device simulations show that the efficiency of future PERC cells can improve up to 1% absolute when optimally charged dielectric coatings are applied both at the front and rear surfaces.

Assessing the Potential of Inversion Layer Solar Cells Based on Highly Charged Dielectric Nanolayers

“…Interface state density ( D it ) of 5 × 10 10 eV −1 cm −2 was set at midgap, 2 × 10 15 eV −1 cm −2 at the conduction band tail, and 8 × 10 14 eV −1 cm −2 at the valence band tail, as has been recently reported. [ 33 ] A schematic of the structure and a band diagram at the interface is shown in the inset in Figure 6a. Klaassen's parameterization was used to model the mobility throughout the sample bulk and in the space charge layer.…”

Highly Improved Mis Photodetector Sensitivity Using Ge Nanocrystals

“…GeO x ) at the Ge NCs-SiO 2 top interface that could affect the electrical and optical properties of Ge NCs. [11] All the samples were then subsequently encapsulated by 45 nm of SiO 2 deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) during an ex situ step. After the SiO 2 capping, all the samples undergo an ex-situ Rapid Thermal Annealing (RTA) at 750°C for 30s under N 2 ambient gas in order to reduce the defects in the SiO 2 matrix and at the two Ge NCs-SiO 2 interfaces.…”

“…However, Ge NCs based micro-electronic devices prototypes still face some challenges such as anomalous electric transport and low optical absorption and emission. [11] All these problems which cause operating uctuations and reduce the devices performances, result from fabrication-related defects such as crystalline defects in the Ge NCs, interfacial states at the Ge NCs/SiO 2 , NCs size inhomogeneity.…”

Mitigating Potential-Induced Degradation (PID) Using SiO2 ARC Layer

“…It has high-temperature stability of up to 1600 • C, making it a useful material for process and device integration [24].…”

“…It has high dielectric strength and a relatively wide bandgap, making it an excellent insulator.  It has high-temperature stability of up to 1600 ˚C, making it a useful material for process and device integration [24]. …”